On 03/01/2012 01:59 PM, Eric Dumazet wrote:> Le jeudi 01 mars 2012 à 13:50 +0100, Rodrigo Moya a écrit :>> the main problem in D-Bus we are trying to solve is the context>> switches, since right now, there is a daemon, which listens on a UNIX>> socket, and all traffic in the bus goes through it, and then the daemon>> has to route the messages it gets on that socket to the corresponding>> place(s). So, every time someone sends a message to D-Bus, since all>> traffic goes through the daemon, dbus-daemon gets waked-up, which is one>> of the biggest bottlenecks we are trying to fix.>> >> That's why we are thinking about using multicast with socket filters, so>> that the daemon only gets traffic it cares about and thus is not waked>> up and context switches don't happen when not needed.>> >> Using message queues, AFAICS, we would have the same problem, as the>> daemon would create the message queue and would get all traffic, right?>> > > This is why I mentioned extensions.

> > Anyway, if you think multicast sockets is the way to go, then you could> setup a virtual network just to be able to use AF_INET multicast.> > Thats probably doable without kernel patching.>

We could use AF_INET multicast on a local machine but we need someordering and control flow requirements that are not guaranteed on UDPmulticast over IP. That's why we thought to add a new address familyAF_MCAST.

To make it a general local multicast solution and not being too specificwe added some flags to control its behavior likeMCAST_MREQ_DROP_WHEN_FULL to decide to either block the sender or dropthe packet when one receiver has its queue full.